Throttle valve operating mechanism



INVENTOR Q1 E z'sz'zzgez:

CLUB,

ATTORNEY Aug. 22, 1933. R, J, EISINGER THROTTLE VALVE OPERATING MECHANISM Filed Feb. 26 1950 ZITN S Patented Aug. 22, 1933 UNITED STATES PATENT oFF cE THROTTLE VALVE OPERATING MECHANISM Rudolph J. Eisinger, Prospect Park, Pa., assignor to Westinghouse Electric & Manufacturing Company, a Corporation of Pennsylvania Application February 26, 1930. Serial No. 431,523

7 Claims.

' moved to the desired position.

The mechanism of the present invention is a modification of the throttle valve operating mechanism described and claimed in the patent of Anthony F. Schwendner, No. 1,769,968, granted July 8, 1930.

vIn accordance with my invention the motor device for operating the throttle valve and the pilot valve which controls the motor device are connected by a follow-up mechanism. The control member is preferably connected to the follow-up mechanism, through which it moves the pilot valve for effecting movement of the motor device. When the motor device brings the throttle valve to the position required by the control member, the follow-up mechanism returns the pilot valveto closed position.

The above and other objects are effected by' my invention, as will be apparent from the following description and claims, taken in connection with the accompanying drawing, forming a part of this application, in which:

The single figure is a diagrammatic view of a throttle valve and operating mechanism therefor applied to a steam turbine, the valve and operating mechanism being shown in section on an enlarged scale.

Referring now to the drawing more in detail, I show a throttle valve 10 interposed in a conduit 11 through which steam or other motive fluid is supplied to a turbine 12. There are several functions of which the operating mechanism for such a throttle valve should be capable. It should be capable of manual control to any extent in either opening or closing direction. It must quickly close the throttle valve when the automatic stop governor operates in response to overspeed of the prime mover. When the throttle valve is closed in response to action of the automatic stop governor, the operating mechanism should not be automatically operable to reopen the throttle valve upon resetting the automatic stop governor. This is to assure that the steam admission shall be restored gradually under full manual control.

The operating mechanism for the throttle valve 10 is indicated generally by the numeral 13 and includes a motor device 14 for actuating the valve, and pilot valve means 15 for controlling the application of fluid pressure to the motor device 14. The motor device 14 comprises a stationary cylinder 17 in which is operatively disposed a piston 18, the latter being connected to the-throttle valve 10 by means of a rod 19. The valve 10 is biased in closing direction by any suitable means, such as a compression spring is fitted in the casing 22. The bushing 23 is formed with an annular row of ports 24, which communicate with the lower end of the cylinder 17 through a passage 26. A second annular row of ports 27 also communicates with the lower end of the cylinder 17 through the passage 26.

A third row of ports29, just above the row of ports 24, communicates with a source of fluid pressure. In the present embodiment, the fluid pressure is developed by a pump 31 driven by the turbine and conveyed through a conduit 32 communicating with the ports 29. Interposed in the conduit 32 is an orifice 33 for restricting the flow ofrfluid.

Above the ports 27 is a row of ports 34'communicating with the upper end of the cylinder 17 through a passage'35. Below the ports 24 is an annular row of discharge ports 36, communicating with a drain conduit 3'7. As shown on the drawing, an annular recess 25 is formed in the position, the auxiliary pilot valve 39 covers the ports 27, and extends a short distance above the upper edges of the ports 27 and. downwardly to within a short distance of the ports 29. A stem 4lcarried by the pilot valve extends downwardly through the lower end wall of the casing 22.

The mechanism for controlling the pilot valve control member, since its position normally-con trols the position of the throttle valve, as Will hereafter be apparent.

A bell crank lever comprising. armsf l and 521' The arm 51 is pivoted. on the sleeve 48 at 50. engages a cam 53 carried by therod 19, while the arm 52 has a slot 54 in which the lower end of;

A spring 55 the pilot valve stem 41 engages. biases the pilot valve upwardly and the bell crank lever in counterclockwise directionfor the 'purpose of maintaining the arm 51 in engagement with the cam 53. The bell crank lever51-52 andthe cam53 constitute a follow-up mechanism for-returning the pilot valve 38 to cut-off position-upon movemnt of the'throttle valve-10.

- An automatic stop governorof well-known design is providedfor eifecting closing of the throttle valve-uponfa predeterminedoverspeed of the turbine 12. It includes a valve 57 communicating withthe lower end 'of'the cylinder 1'7 through a conduit 53;- The valve 57 is normally-held closed by a lever 59 pivoted at 61. A trip finger 62'piv-' oted at 63' normally engages the left-hand arm of the lever 59. A weight 64 is mounted on the shaft and. is adapted to move outwardly to strike the trip finger 62-wl1en the shaft-exceeds the predeterminedioverspeed; 1 r

.For the purpose of holding the throttle'valve -10tightly on its' seat when the turbine 12 is shut down, a stem 65 may be screw-threaded through 4the upper end wall of the cylinder 17; It is pro- -.vided with a hand wheel66 whereby it may be brought intoabutting engagement with the piston 18. Normally the stern'65 is positioned above the upper limitof travel of the piston- 18.

,valve, the sleeve 48 is moved to the right by rota tion of the hand wheel 47 in the opposite direction; This movement of the sleeve permits a ro- 1., Theoperation of the above-described appae ratus is as follows:

Assume the. apparatus to be in theposition shown on the drawing and that it is desired to movethe. throttle valve 10 in opening direction under manual control. rotated to move the sleeve 48 to the left. movement of the sleeve causes the bell crank 'lever 51-52 to move angularly in clockwise di- The hand wheel 47 is This rection about the pivot 50, moving the pilot valve 38 downwardly- The ports 24 are placed in comthe lowerend of'the cylinder 17 to move the piston 18 upwardly. The upward movement of .the cam 53 permits the bell crank lever ESL-52 continue the; opening'movement of the throttle valve, movement of the sleeve 48 tolthe left is continued by rotation of .the hand wheel 4'7.

To effect a closing movement of the throttle tary movementof the bell crank lever 5l-' 52 in counter-clockwise direction and an upward (movement of the pilot valve 38. The ports24' are now placed in communication with the discharge ports 36, whereupon the spring 21 moves the pis ton 18 downwardly, the fluid pressure in the lower end of the cylinderpl'l'escaping through the ports 24 and 36 to the drain conduit 37. The downward movement of the cam 53 moves the bell cranklever 51- 52 inclockwise direction, re-

turning the pilot valve 38 to cut-off position.

In the operation above described for opening the throttle valve, the auxiliary pilot valve 39 moves downwardly with-the pilot valve 38, but as it normally extends above the upper edges of the ports 27, this movement has no effect if the hand wheel 47 is not rotated too rapidly. If it is rotated too rapidly, that is, if the auxiliary pilot valve is, moveddownwardly a sufficient distance to uncover the ports 2'7 before the piston18 can effecta return'movement of the pilot valve, the fluid pressure in the lower end of the cylinder 17 escapesthrough the ports 27, and through the ports 34 and the passage 35 to the upper end of the cylinder 17. The ports 27 permit escape of I fiuid'muchmore rapidly than it can be supplied through the orifice 33, so that the spring 21 is rendered effective to close the throttle valve. The auxiliary pilot valve 39 continues to move downwardly, and after moving some distance covers the ports 29, thereby-cutting off the admission of fluid pressure to the cylinder 17.

The discharge of the fluid from the lower end of the" cylinder 17 to the upper endthereofpertravel, which 1 is the position thereof effecting closing of the throttle valve under manual control, inorder to move the auxiliary pilot valve 39 i to a position closing the ports 2'7. I The valve may then be opened by moving the sleeve 48 to the left asdeScribed-abOVe. v

Now assume the throttle valve tobe open and The weightmember 64-strikes the trip finger 62, which disengages "the lever 59. Thelatter is free to move angularly about its pivotfil in counterclockwise direction, which it does under force of the valve 57 on which the fluid pressure acts in opening direction. The fluid in the lower end of the cylinder 17 being free to escape through the valve 57, the spring 21 moves the piston 18 downwardly. The resulting downward moveuncovers the ports 27' to permit a further discharge of fluid to the upper end of the cylinder 17, and to prevent reopening of the throttle valve when the automatic stop governor has been reset until the sleeve or control member 48 has been 'moved to substantially the right-hand end of its travel to move the auxiliary 'pilotvalve '39 upwardly to close the ports'27. I c

From the above description, it will be seen that I have provided a mechanism for power actua L tion of the throttlevalve in both opening and closing directions to open, closed or any intermediate position'thereof. It will also be noted that in thenormalopen position of the throttle -theshaft to exceed the predetermined overspeed.

-ment of the auxiliary pilot valve 39, as before, munication with the ports .29, and fluid under" pressure-is." supplied through the passage 26 to valve, the flow of fluid into or out of the lower.

end of the cylinder'l'l is cut off, and a: continual flow of fluid under pressure,v except to make up for leakage, is not required.

While I have shown my invention inbut one form, it willbe obvious tothose skilled in the art that it is not so limited, but"'issusceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. The combination with a valve, of an operating mechanism therefor comprising a piston connected to the valve, a cylinder for the piston, pilot valve means located exteriorly of the cylinder for controlling the application of fluid pressure to the piston, a control member movable tovarious positions corresponding to open, closed and intermediate positions of the valve, means controlled by the control member for moving the pilot valve to effect movement of the valve to the position thereof corresponding to the position of the con-- trol member, means for returning the pilot valve means to cut-oil position when the valve is brought to said corresponding position, and means whereby, when the valve is in closed position, the same cannot be opened until the control member is brought to the position corresponding to closed position of the valve.

2. In an operating mechanism for a valve, the combination of a piston connected to the valve, a cylinder in which the piston operates, means biasing the valve in closing direction, means for admitting fluid under pressure to that end of the cylinder in which it acts on the piston in valveopening direction, pilot valve means for controlling the admission of fluid pressure to said end and the discharge of fluid therefrom, a con trol member for controlling the pilot valve means to effect open, closed or intermediate position of the valve, follow-up mechanism for returning the pilot valve means to closed position when the valve has been moved to the position determined by the control member, and auxiliary pilot valve means operative to release the fluid pressure from said end of the cylinder when the valve moves a predetermined distance to closed position from the position determined by the control member.

3. In an operating mechanism for a valve, the combination of a piston connected to the valve, a cylinder in which the piston operates, means biasing the valve in closing direction, means for admitting fluid under pressure to thatend of the cylinder in which it acts on the piston in valveopening direction, pilot valve means for controlling the admission of fluid pressure to said end and the discharge of fluid therefrom, a control member for controlling the pilot valve means to effect upon, closed or intermediate position of the valve, follow-up mechanism for returning the pilot valve means to closed position when the valve has been moved to the position determined by the control member, trip means adapted to efiect closing of the valve independently of the position of the control member by releasing the fluid pressure from said end of the cylinder, and auxiliary pilot valve means operative to release the fluid pressure from said end of the cylinder when the valve movesa predetermined distance to closed position from the position determined by the control member.

4. In an operating mechanism for a valve, the combination of a piston connected to the valve, a cylinder in which said piston operates, a spring fluid pressure to said piston in valve-opening direction to provide movement of the valve to the position corresponding to the position of the control member, a stationary casing for said pilot valve, means for releasing the fluid pressure from the piston independently of the pilot valve, and an auxiliary pilot valve connected to said pilot valve and disposed Within said casing, said auxiliary pilot valve being operable to release the fluid pressure from said piston when the valve operated thereby moves a predetermined distance in closing direction beyond the position corresponding to the position of the control member.

5. In an operating mechanism for a valve, the combination of a piston connected to the valve, a cylinder in which the piston operates, means biasing the valve in closing direction, pilot'valve means for controlling the application of fluid under pressure to that end of the cylinder in which it acts on the piston in valve-opening direction, a control'member for controlling. the pilot valve means to effect open, closed or'intermediate position of the valve, follow-up mechanism for returning the pilot valve means to closed position whenthe valve has been moved to the position determined by the control member, and auxiliary pilot valve means operative to release the fluid pressure from said end of the cylinder when thevalve moves a predetermined distance to closed positionfrom the position determined by the control member.

6. In an operatingmechanism for a valve, the combination of a motor device connected to the valve, pilot valve means controlling the application of fluid pressure to said motor device, followup mechanism connecting the motor device and the pilot valve means for moving the latter toward cut-off position upon movement of the motor device, control means acting on said follow-up mechanism for moving the pilot valve means to effect movement of the motor device, trip means adapted to supersede the pilot Valve means and to control the motor device to close the valve, and means preventing operation of the motor device to open the valve when the trip means operates until the control means is operated for effecting substantially closed position of the valve.

7. In an operating mechanism for a. valve, the combination of a piston connected to the valve, a cylinder in which the piston operates, means biasing the valve in closing directiompilot valve the pilot valve means for moving the latter tobiasing the valve to closed position, a control ward cut-ofi position upon. movement of the piston, controlling means acting on said follow-up mechanism forcontrolling the pilot valve means to effect open, closed or intermediate position of the valve, and auxiliary pilot valve means operative to release the fluid pressure from said piston when the valve moves a predetermined distance to closed position from the position determined by the control means.

RUDOLPH J. EISINGER. 

